35 lines
971 B
JavaScript
35 lines
971 B
JavaScript
/**
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* Initializes metadata for an axis and its cells.
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* This data is used to determine which cells are visible given a container size and scroll position.
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*
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* @param cellCount Total number of cells.
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* @param size Either a fixed size or a function that returns the size for a given given an index.
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* @return Object mapping cell index to cell metadata (size, offset)
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*/
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export default function initCellMetadata(_ref) {
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var cellCount = _ref.cellCount,
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size = _ref.size;
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var sizeGetter = typeof size === 'function' ? size : function () {
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return size;
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};
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var cellMetadata = [];
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var offset = 0;
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for (var i = 0; i < cellCount; i++) {
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var _size = sizeGetter({
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index: i
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});
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if (_size == null || isNaN(_size)) {
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throw Error("Invalid size returned for cell ".concat(i, " of value ").concat(_size));
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}
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cellMetadata[i] = {
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size: _size,
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offset: offset
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};
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offset += _size;
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}
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return cellMetadata;
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} |